Beginners Guide to Canister Filtration Systems

Like most common forms of aquarium filtration, a canister filter provides chemical, biological and physical filtration by removing water from the aquarium via an intake tube, passing the aquarium water over a series of filtration media housed within a pressurized canister, and they returning the filtered water to the aquarium via a spray bar or spray nozzle. The unique form factor of the canister filter allows for a lot of flexibility in terms of where the filter is located. Since flexible tubing is used for both the intake and return, a canister filter can be located underneath, behind or off to the side of the aquarium, with the length of the tubing and the strength of the return pump within the canister filter being the only real limiting factors.

The sealed and pressurized design of the canister filter also allows for very quiet operation, as the noise associated with water overflowing from the fish tank or flowing from one chamber to another as in a non-sealed aquarium filter design are kept to an absolute minimum. Being a sealed design, the canister filter can also be disconnected from the intake / return tubing and carried away for maintenance and cleaning. This design allows the hobbyist the flexibility of maintaining and cleaning the filter in a location better suited for the activity and not being forced to work underneath the aquarium or in other less than desirable locations.

How do canister filters work?

Canister filters work by drawing water from the aquarium via a lift tube and through plastic tubing into the externally located canister filter. This is done via a pump that is typically located in the bottom of the canister filter. The extracted water is forced through a series of filter media layers located within the pressurized canister filter. While the exact flow of the water through the filter media can vary by models and brands of canister filters, a typical scenario has the water first passing through media designed to remove physical particles from the water, then through biological filter media and lastly through media designed for chemical filtration, before being returned to the aquarium back through plastic tubing connected to either a nozzle or spray bar.

How well do they work compared to other aquarium filtration techniques?

There are a number of different filter types available within the aquarium hobby, and depending on the particular needs of an aquarium setup or the specific requirements of a hobbyist, they all have their niche. This being said, canister filtration is considered to be one of best forms of filtration for a wide variety of aquarium setups ranging from smaller freshwater or marine aquariums like nano cubes, all the way up to very large freshwater aquariums housing large Cichlid species and even larger FOWLR or predator marine fish aquariums. Hobbyists can also use multiple canister filters on the same aquarium, which allows canister filters to scale up and handle even extremely large aquariums (300 gallons plus) or aquariums with high bio-load species like Peacock Bass or freshwater Stingray.

While canister filtration can be used successfully on marine reef or larger marine fish aquariums, they are probably not the best option overall for these types of setups. Generally these larger saltwater fish or reef aquariums require large wet/dry, sump or refugium based filtration with additional foam fractioning filters like Protein Skimmers in order to provide the necessary level of filtration for complex marine aquarium environments.

Overall though, canister filters do provide high quality filtration, have low power consumption, are cost effective and easy to maintain, which makes them a great choice for most all freshwater community aquarium setups, most all Cichlid aquarium setups, marine nano cubes and moderately sized FOWLR setups and as additional filtration on larger aquarium setups where multiple forms of filtration are required.

What sort of maintenance do canister filters require?

Canister filters are designed with efficiency, application flexibility and ease of maintenance. The main portions of the filter that require periodic maintenance are contained within the main housing of the filter, where they can be easily transported to a utility sink, outside or other convenient location for cleaning. Aside from clearing algae or debris from the return nozzle or spray bar, the bulk of the maintenance required to keep a canister filter running smoothly and efficiently is centered around the chambers containing the filtration media inside the canister.

Cleaning a canister filter mostly revolves around cleaning or changing the filter pad that captures physical particles from the water and changing out any filter bags containing activated carbon or other chemical media. The biological media (bio balls or ceramic media) typically only needs to be rinsed off from time to time if physical debris is able to build up within the tray containing the bio media. Be sure to use aquarium water or non-chlorinated tap water to rinse off the bio media, this is important in order to not kill off any of the beneficial bacteria living on the media by putting it in contact with the chlorine present in most tap water. Hobbyists should also occasionally pull out all of the media trays and rinse and wipe down the inside of the canister to remove any algae growth or detritus that has built up on the inside of the filter, as this will reduce water flow and ultimately reduce the effectiveness of the filter.

In terms of how often a canister filter should be cleaned, it varies widely based on the sizing of the canister filter vs. the aquarium size, the fish load, the type of fish and feeding regime; however, it is safe to say that most canister filters will need some attention basic cleaning of the physical filter pad every 1 to 2 months and a more thorough cleaning at least every 4 months. While many hobbyists go longer periods of time; often up to 6 months, their filter are most likely quite dirty and their capability significantly degraded by 6 months of use.

Our opinion on the best uses for canister filters

So canister filters come in a wide variety of models, designs and capabilities, but is canister filtration the right filtration for your particular tank?

The short answer is that it depends mostly on the size of your aquarium and your budget. While in theory a canister filter or a combination of multiple canister filters can provide proper filtration for essentially any home aquarium (assuming you don't have a 2000 gallon home aquarium), it may not always be the best form of filtration or the most cost effective form of filtration.

Here are the best uses for canister filtration, listed by the most ideal to least ideal situation:

Medium to large sized freshwater fish aquariums: These are aquariums that are generally between 30 to 300 gallons in size and contain Freshwater community, New World Cichlid or African Cichlid fish species.

Larger New World Cichlid or African Cichlid freshwater fish aquariums: These are larger aquariums 125 to 450 gallons in size where multiple high-end canister filters can be combined to handle the substantial filtration requirements of larger Cichlid species.

Smaller freshwater fish aquariums: These are freshwater fish or planted aquariums that typically range between 10 to 30 gallons in size. While these can be adequately filtered via power filters or even internal filters, a small canister filter will also do an excellent job at a slightly higher upfront cost.

Smaller to medium sized marine fish aquariums: These are generally fish-only or FOWLR (fish only with live rock) aquariums ranging from 20 to 125 gallons in size. While a canister filter is not the ideal form of filtration for a marine aquarium, when combined with a hang-on protein skimmer it can provide excellent filtration for marine aquariums setups housing primarily fish.

Here are the situations where a canister filter is either a poor choice or won't work well at all:

Coral reef aquariums: These are marine aquariums supporting a variety of Corals, invertebrates and fishes, which essentially require sump based filters, protein skimmers, extra internal water flow via powerheads or wave makers and either refugiums or algae scrubbers to really thrive. While canister filters can provide supplemental filtration in this type of aquarium setup, they are poorly suited to be the main filtration method.

Extra large freshwater or marine aquariums: These are tanks that exceed 450 gallons and are not well suited for even multiple canister filters. Due to their large scale, these tanks are better suited for larger scale filtration techniques similar to those found in commercial aquaculture, ie. bead filters, tower filters, etc.

Nano aquariums: These are smaller aquariums (often cube shaped) that are intended for micro environments like mini reefs or freshwater shrimp. Generally this type of setup can be filtered more efficiently and at a lower cost by filtration techniques other than canister filters.

AquariumDomain.com Members, if you have questions or suggestions on how to make this blog post better please comment below or discuss on our forums.

Hey Rodney! Thanks for checking out the Pleco L-Number blog. We will be updating the blog continuously until we have from L001 - L600 and beyond as they are discovered. We will update the top line of the blog to show the status and hopefully have it all done over the next few weeks!